Influence of Smoking in the Clinical Outcomes of Distal Radius Fractures

Abstract

Introduction  There are various studies that reviewed the effect of cigarette smoking in fracture healing process. Nonunion, delayed union, and residual pain are the significant risk factors associated with smoking and fracture healing. Little has been known about the impact of smoking in distal radius fracture healing. We intend to explore in brief the effect of smoking in distal radius fracture healing and comparing it with nonsmokers having the same fracture fixation and analyze the outcomes with respect to fracture healing and return of function.

Materials and Methods  Of the total 186 patients, 92 were included in the study with ( n = male: 31, female: 61) mean age of 60.2 years. They were divided into two groups: smoking ( n = 43) and nonsmoking ( n = 49). All had surgical fixation of the distal radius with volar locking plate and started on early mobilization. The range of motion of the wrist, grip, visual analog scale, quick disabilities of the arm and shoulder and hand score, Mayo wrist score, and bone healing period were noted between these two groups and compared with statistical analysis.

Results  The mean follow-up period was 8.7 months. There was a significant association of young age and male patients having distal radius fractures in the smoking group ( p < 0.05). All fractures healed well in both groups without complications. There was no significant difference between these two groups in terms of range of motion, grasp, bone healing period, and functional outcomes.

Conclusion  Despite the well-known fact that, smoking has negative implications in the fracture healing process, we found group of patients (smoking and nonsmoking) with distal radius fractures treated by volar locking plates healed well with good radiological union and excellent functional outcome There is no significant influence of smoking in distal radius fracture fixation.

Introduction

Cigarette smoke has many compounds harmful to the human body. 1 2 3 4 Nicotine is an addictive part contained in these cigarettes and has deleterious influence on many vital organs. 1 4 5 The effect of cigarette smoking on bone metabolism has been reported in many studies that observed that bone density is reduced in elderly and postmenopausal smokers. 3 6 Nicotine causes vasoconstriction and tissues hypoxemia, thus delaying fracture healing. 7 8 Nonunion, delayed union, and residual pain are the complications of smoking associated with fracture healing. 9

Less is known about the impact of cigarette smoking and the outcome of distal radius fracture healing. We proposed to study the influence of cigarette smoking in distal radius fracture healing in two group of patients (smokers and nonsmokers) and compared the radiological and functional outcomes in them.

Materials and Methods

This was a retrospective study approved by the ethics committee for medical research board in our university (No. 17–250). Informed consent was obtained from all patients. There were 207 patients operated for their distal radius fracture between October 2012 and May 2018. Of these, 186 patients had followed up details over 6 months after surgery. Our study eligibility criteria included pre- and postoperative radiological studies, regular follow-up during the entire course of the study, and functional assessment at the end of the study. Only 92 patients met these criteria. In these, there were 31males and 61 females with a mean age of 60.2 (range: 19–86 years) years. Right and left wrist were equally involved in our study ( Fig. 1 ). We divided the group into smoking and nonsmoking groups for comparison and statistical analysis of the functional outcomes.

Fig. 1.

Process of selecting subjects. Of 207 patients with distal radius fractures treated with surgery using a volar locking plate at our hospital between October 2012 and May 2018, 186 patients could be followed up for 6 months or longer after surgery. Of these patients, the presence or absence of cigarette smoking could be confirmed in 92 patients and these patients were selected for the subjects.

The smoking group has 43 patients divided as 25 males and 18 females with a mean age of 56 years (range: 22–86 years). The nonsmoking group had 49 patients consisting of 6 males and 43 females with a mean age of 63.9 years (range: 19–84 years). The AO classification for distal radius fracture was used in our study ( Table 1 ). Type A was seen in 17 patients (A2: 13, A3: 4), B in 4 (B3: 4), and C in 71 (C1: 50, C2: 7, C3: 14). In the smoking group, the fracture type was A in 6 (A2: 3, A3: 3), B in 2 (B3: 2), and C in 35 (C1: 22, C2: 4, C3: 9), and in the nonsmoking group, A in 11 (A2: 10, A3: 1), B in 2 (B3: 2), and C in 36 (C1: 28, C2: 3, C3: 5).

Table 1. Backgrounds of the smoking and nonsmoking groups of patients with distal radius fractures treated with surgery using a volar locking plate.

Variable		Smokers ( n = 43)	Nonsmokers ( n = 49)	p -Value
Abbreviations: AO, Arbeitsgemeinschaft für Osteosynthesefragen; NS, not significant. ap < 0.05. b p < 0.01.
Age (years)		56.0 ± 13.8	63.9 ± 14.9	< 0.05 a
Sex				< 0.01 b
Male		25	6
Female		18	43
Affected wrist				N.S.
Right		18	28
Left		25	21
AO classification				N.S.
	A2	3	10
	A3	3	1
	B3	2	2
	C1	22	28
	C2	4	3
	C3	9	5

These 92 patients had volar locking plate for their distal radius fracture. All had early mobilization of the wrist soon after the surgery. Most importantly, they were advised strictly to refrain from smoking. Serial posteroanterior (PA) and lateral radiographs were done to assess the fracture healing. The appearance of bridging callus in three cortices was taken as the criteria for bone union. 10 The range of motion at the wrist (flexion, extension, forearm pronation, forearm supination), grip (% of the healthy side), visual analog scale (VAS), evaluations of the wrist joint function: quick disabilities of the arm and shoulder and hand (QuickDASH) score and Mayo wrist score, and the fracture healing period were evaluated in both groups and compared using the t -test.

The entire data were presented as the mean ± standard deviation. GraphPad Prism 7 (GraphPad Software, Inc., La Jolla, California, United States) was used for statistical analysis. The χ square test was used to interpret the influence of age, gender, fracture side, and the fracture type on the fracture healing. A p- value < 0.05 was considered to indicate a statistically significant difference. Power analysis was performed by free software G* Power 3.11 Moreover, on postoperative radiography, the PA view was used to determine radial inclination (RI) and volar tilt (VT) was evaluated on lateral view.

Results

The mean follow-up period was 8.7 (6–26) months. There was a significant association of young age and male patients having distal radius fractures in the smoking group ( p < 0.05). But the fracture side and pattern of fracture had no significance effect on the outcome. The range of motion of the wrist was flexion, 75.5 ± 9.2 degrees; extension, 76.1 ± 9.3 degrees; forearm pronation, 83.0 ± 7.9 degrees; forearm supination, 83.7 ± 6.4 degrees; the grip (% of the healthy side), 77.4 ± 28.6%; VAS, 1.2 ± 1.3/10; QuickDASH score, 10.8 ± 11.1/100; Mayo wrist score, 90.7 ± 9.1/100; bone healing period, 88.1 ± 37.7 days in the smoking group. In the nonsmoking group, the range of motion of the wrist was flexion, 72.0 ± 14.0 degrees; extension, 73.5 ± 11.4 degrees; forearm pronation, 82.6 ± 9.7 degrees; forearm supination, 82.0 ± 12.8 degrees; the grasp (% of the healthy side), 78.9 ± 26.5%; VAS, 1.5 ± 1.7/10; QuickDASH score, 10.9 ± 10.7/100; Mayo wrist score, 90.5 ± 10.2/100; bone healing period, 75.7 ± 48.0 days. Interestingly, we found no significant difference between these two groups in terms of range of motion, grasp, bone healing period, and functional outcomes ( Table 2 ). In this study, the effect size by t -test is d = 0.2873 and verification power is 1-β = 0.3775916, and the number of cases may be insufficient to obtain sufficient verification power. Postoperative radiographic parameters were VT 11.1 ± 7.3 degrees, RI 21.7 ± 4.6 degrees in the smoking group, and VT 12.2 ± 9.4 degrees, RI 21.8 ± 4.8 degrees in the nonsmoking group. There was no significant difference in VT and RI between both groups.

Table 2. Postoperative clinical outcomes of the smoking and nonsmoking groups of patients with distal radius fractures treated with surgery using a volar locking plate.

	Smokers ( n = 43)	Nonsmokers ( n = 49)	p -Value
Abbreviations: QuickDASH, quick disabilities of the arm, shoulder and hand; VAS, visual analog scale.
Flexion (degrees)	75.5 ± 9.2	72.0 ± 14.0	0.55
Extension (degrees)	76.1 ± 9.3	73.5 ± 11.4	0.86
Pronation (degrees)	83.0 ± 7.9	82.6 ± 9.7	0.80
Supination (degrees)	83.7 ± 6.4	82.0 ± 12.8	0.44
Grip (% of the healthy side)	77.4 ± 28.6	78.9 ± 26.5	0.80
VAS	1.2 ± 1.3	1.5 ± 1.7	0.39
QuickDASH score	10.8 ± 11.1	10.9 ± 10.7	0.98
Mayo wrist score	90.7 ± 9.1	90.5 ± 10.2	0.93
Hearing periods (days)	88.1 ± 37.7	75.7 ± 48.0	0.19

Discussion

Cigarette smoking has a negative influence on the fracture healing because of nicotine-induced vasoconstriction and hypoxemia. They cause fracture delayed union, nonunion with residual pain. 7 8 9 Nonunion per say in the distal radius fracture is very rare because of the metaphyseal region and good blood supply 12 13 Few studies have shown that nonunion of distal radius fracture reduces the range of motion and grip strength. 14 15 16 17 There was no nonunion reported in our study in both groups (smoking and nonsmoking). All patients had fracture union with good range of motion and excellent grip strength.

There is an argument that cigarette smoking may mimic or be considered analogous to an open fracture causing severe soft tissue damage because of nicotine-induced vasoconstriction. 4 18 Taking this into account, our patients who had low energy trauma (fall) had no nonunion in both smoking and nonsmoking groups contrary to the smoking study by Scolaro et al. 4 Cigarette smoking promotes tissue fibrosis and adhesion through the signaling pathways of extracellular-signal-regulated protein kinase (ERK) and transforming growth factor-β (TGF-β). 19 Subsequent to this fibrous tissue formation, reduction in microvasculature, and reduced blood supply, smokers do experience residual pain. 20 This pain may not be seen in smokers with distal radius fractures. 12 13 Our study had no residual pain in the smoking and nonsmoking groups during the entire course of our study.

Sun et al noted a significant VAS in smokers during their mobilization period in elbow osteoarthritis and trauma groups. 19 But, Mehta et al found smoking was not a risk factor in patients with chronic pain following distal radius fractures. 21 Sugiyama et al found that volar surgical approach preserves the blood supply to the distal radius and is not associated with residual pain and joint pain. 22 Since all of our patients had the same volar approach for surgical fixation of the distal radius, we agree with these authors and recommend this approach as it preserves the rich blood supply and may help reduce postoperative residual pain.

There are several limitations in this study. The number of patients was small and insufficient for statistical analysis. The effect size by t -test is d = 0.2873, verification power is 1-β = 0.3775916, and the number of cases may be insufficient to obtain sufficient verification power. Thus, the maximum possible number of patients was included. We understand that in the future it is necessary to perform a study with an increased number of patients. Moreover, this study was retrospective study with more young aged smokers, less elderly nonsmokers, and gender being a confounding factor. We need to have a large prospective study comparing the fracture healing process in the young and elderly smokers and nonsmokers rather than comparing them all in one study. 4 23 We did not take into account smoking details such as number of cigarettes and duration of smoking. Despite these limitations, our study proved the hypothesis that there is no significant influence of smoking in the distal radius fractures in terms of radiological union, range of movements, grip strength, residual pain, and functional outcomes.

Conclusion

Though cigarette smoking has been noticed to nicotine-induced vasoconstriction, hypoxemia, fibrous adhesions residual pain and contribute to nonunion of fractures, our study found none of these. Our study found that smoking had statistically no significant impact on distal radius fracture healing. The smoker and the nonsmoker group did equally well in terms of bone union and functional outcome.